Image And Part Recognition Technology

ABSTRACT

A system and method for recognition of images may include the use of alignment markers. The image recognized may be a pattern from an array, a character, a number, a shape, and/or irregular shapes. The pattern may be formed by elements in an array such as an identification marking and/or a sensor array. More particularly, the system and method relate to discriminating between images by accounting for the orientation of the image. The size and/or location of alignment markers may provide information about the orientation of an image. Information about the orientation of an image may reduce false recognitions. The system and method of image recognition may be used with identification markings, biosensors, micro-fluidic arrays, and/or optical character recognition systems.

PRIORITY CLAIM

This application claims the benefit of U.S. Provisional Application No.60/471,102 entitled “A NEW IMAGE AND PART RECOGNITION TECHNOLOGY,” filedMay 16, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of discriminating images. Moreparticularly, the invention relates to a method of image and patternrecognition using a computer.

2. Description of the Relevant Art

Computerized identification systems are useful in a variety ofapplications. Products in a supermarket are branded with a barcode, theuniversal product code (UPC), that represents a ten digit number. Aproduct UPC may identify the manufacturer and item number, which arecorrelated in a database to the product's price. Barcodes may be printedon a variety of surfaces and in a range of sizes. A laser scanningsystem is often used to recognize bar codes. Accurate readings may beobtained despite partial obscurement and nonuniform orientations. Thebarcode system is limited. The widths and spacing of a series of barswithin a code represents a number. Thus, an accurate knowledge of thewidths and spacing of the series of bars is crucial for accuratereadings. As a barcode decreases in size, the bar widths and spaces canbe obscured, because of resolution limitations.

Dot patterns may have advantages over barcode systems. FIG. 1 depicts a5×5 dot pattern. Dots may be easier to make via photolithography, aprocess sometimes employed in making sensors. Additionally dots can beeasily recognized in an image even if they are very small. Due toresolution limitations, as barcodes decrease in size accuraterecognitions become more difficult. The dot pattern in FIG. 1 may not bea robust image identification system alone. The pattern can be rotated,flipped, and/or positioned upside-down. Patterns that are symmetricabout a central axis may be misread if the pattern is rotated and/ormirrored.

FIG. 2 depicts two dot patterns with dots arranged in “M” and “W”formations with alignment markers positioned outside the patterns.Without the alignment markers, the patterns may become indistinguishableif one of the dot patterns is rotated 180 degrees. A similar situationarises if the dots in the pattern are arranged to resemble a “6” or a“9”. Some identification systems position an additional dot or line asan alignment marker to facilitate identification of patterns.

FIG. 3 depicts dot patterns with a single central alignment mark and asecondary off-center alignment mark. Without secondary alignment marks,the patterns are indistinguishable if one of the dot patterns ismirrored. Failure of an image recognition system may occur if a patternwith a single central alignment dot is mirrored, particularly if analignment mark is positioned along an axis of symmetry.

FIG. 4 a depicts dot patterns that appear identical if the unfilled dotsare ignored or not detectable when one pattern is rotated 180 degrees.Often only dots that produce a signal are detectable by a detector; andso when attempting to recognize a pattern, two patterns that may notappear identical if all dots are detectable will appear identical due tothe detector used. In FIG. 4 b, mirroring may cause two distinctpatterns to resemble each other. The addition of a second alignment dotdoes not aid in distinguishing the rotated or mirrored pattern. Whileindividuals may be able to distinguish between the rotated and mirroredpatterns with two properly positioned alignment dots, a computer basedrecognition system may have difficulty with only two alignment marks. Ina computer based recognition system, the alignment marks, may beidentified first and then the dot patterns may be identified. This maybe a source of some of the difficulty a computer-based system mayencounter with only two alignment dots. While the angle of an array maybe determined with two alignment dots, the mirroredness of an array cannot be determined. The system may incorrectly identify patterns withoutinformation regarding the mirroredness of an image. Additionally, withonly two alignment dots/markers, the identification systems must searcha large area around the alignment markers to find the complete array.

SUMMARY OF THE INVENTION

Herein we describe systems and methods for recognizing images usingalignment markers. The system and method of image recognition may beused with arrays, analyte arrays, biosensors, micro-fluidic arrays,and/or optical character recognition systems. The image recognized maybe one or more patterns from an array, one or more characters, one ormore numbers, one or more shapes, and/or one or more irregular shapes.Patterns may be printed or displayed on an object. Alternatively, apattern may be generated by an array by a response of sensing elementsin the array to an analyte in a fluid.

In one embodiment, an identification marking may be used to identify anobject. Identification markings may be printed on the object, printed onpackaging surrounding the object, or printed on a label attached to theobject. In other embodiments, the identification marking may be formedas part of the object or embedded within the object. The identificationmarking may include an array of a plurality of elements. The elementsmay be arranged in a predetermined pattern that is unique for the objectto which the identification marking is coupled.

During use, a detector may scan an identification marking. In manyinstances, the identification marking may be in a random orientationwith respect to the detector. Thus, an array displayed on theidentification marking may be rotated or otherwise disoriented withrespect to the detector. Generally, in order to determine the pattern adetector calculates the proper orientation of the array before analyzingthe pattern. In one embodiment, three or more alignment markers arepositioned proximate to the array. The alignment markers are positionedsuch that the orientation of the array may be determined based on theposition of the alignment markers.

Identification of the alignment markers may be facilitated by designingalignment marks that have a detectable property that is different fromthe elements of the array. In one embodiment, the alignment markers mayhave a shape and/or size that is different from the shape and/or size ofthe elements. Additionally, each of the alignment markers may bedifferentiated from the other alignment markers by shape and/or size.The shape and/or size of the alignment markers may be used to determineinformation regarding the array. For example, the alignment markers mayhave a size that is a function of, but not equal to, the size of theelements. By determining the size of the alignment markers, the size ofthe sensing elements may be determined. In another embodiment, thedistance between the alignment markers may be used to determineinformation regarding the array. In one embodiment, the distance betweentwo of the alignment markers may be a function of the size of theelements and/or the distance between the elements. In an embodiment, oneor more alignment markers may be used to indicate a center of the array.In one embodiment, alignment markers may be positioned along adjacentedges of an array.

The elements may be arranged in a pattern that may be used to identifyan object. For example, the elements may be arranged in the form of analphanumeric character. The elements may be oriented in positions of animaginary array. For example, one or more alphanumeric characters may beformed using an array of elements as a template. During use, only theelements that are needed to form the alphanumeric characters may bevisible to a detector, the unused positions within the array beingnon-visible. Typical dot matrix type representations of alphanumericcharacters are well known and may be used to form patterns in on anarray template.

The determination of patterns accurately may be influenced by thereadability of the elements. If one or more of the elements is notproperly read, or is in some way disfigured to render the elementunreadable, the pattern may be incorrectly identified. In oneembodiment, on or more error checking elements may be placed within thearray. The error checking elements may be used to monitor thereadability of the elements. For example, if one or more of the errorchecking elements is not correctly read, then the detector may rejectthe identification marking and signal that the identification marking isnot readable.

A method of using the identification marking to identify an objectincludes passing the object by a detector such that the detector canscan the identification marking. The identification marking includes anarray of a plurality of elements. Three or more alignment markers may bepositioned proximate to the array. After the identification marking isscanned, the detector determines the identity and position of each ofthe alignment markers. The properties of the alignment markers may beused to identify properties of the array such as, but not limited to,the size of the array, the size of the elements, the spacing of theelements within the array, and the center of the array. This informationmay be used to determine the pattern on the identification marking andthus the identity of the object.

The alignment markers may be used to determine a number of properties ofthe array. For example, the array may be rotated with respect to thedetector coordinate system. The alignment markers may be used todetermine the rotation of the array with respect to the detectorcoordinate system. Additionally, the array may be mirrored. For example,if the identification marker is substantially transparent, the elementsmay be detected from either a front side or a back side. If the image isproperly viewed from the front side, analyzing the back side of thearray may give a pattern that is a mirror image of the proper pattern.The alignment markers may be used to determine if the detector hascaptured a mirrored image of the array. After the pattern is properlyoriented, the pattern may be detected and identified by comparing thepattern to a database of predefined patterns.

In addition to identification of objects, a similar system and methodmay be used to identify analytes in a fluid. In one embodiment, a sensorarray may be used to identify one or more analytes in a fluid. Analytesgenerally includes any chemical that is carried by or dissolved in afluid. The sensor array may include an array of a plurality of sensingelements. One or more sensing elements may be configured to produce adetectable signal in the presence of an analyte.

During use, a sensor array may be contacted with a fluid containing oneor more analytes. A detector may scan the sensor array. In oneembodiment, three or more alignment markers are positioned proximate tothe sensor array. The alignment markers are positioned such that theorientation of the sensor array may be determined based on the positionof the alignment markers. As described above, many properties of thesensor array may be determined by analysis of the alignment markers. Theidentity of the analyte may be determined based on the pattern ofsensing elements that produce a detectable signal.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention may become apparent uponreading the following detailed description and upon reference to theaccompanying drawings in which:

FIG. 1 depicts an embodiment of a dot array.

FIG. 2 depicts an embodiment of dot arrays that are indistinguishableupon rotation.

FIG. 3 depicts an embodiment of dot arrays that are indistinguishablewhen mirrored.

FIG. 4 a depicts an embodiment of unique arrays that appearindistinguishable when one array is rotated.

FIG. 4 b depicts an embodiment of unique arrays that appearindistinguishable when one array is mirrored.

FIG. 5 depicts an embodiment of computer based identificationmisreading.

FIG. 6 depicts an embodiment of an array that is rotated.

FIG. 7 depicts an embodiment of an array including three alignmentmarkers.

FIG. 8 a depicts an embodiment of a dot array that is numbered for usewith Hamming Code error checking.

FIG. 8 b depicts an embodiment of a Hamming coded dot array.

FIG. 9 depicts an embodiment of an image for recognition.

FIG. 10 depicts an embodiment of an image after color filtering.

FIG. 11 depicts an embodiment of an image after median filtering.

FIG. 12 depicts an embodiment of an image after edge detection.

FIG. 13 depicts an embodiment of an image after shape detection.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and may herein be described in detail. It shouldbe understood, however, that the drawing and detailed descriptionthereto are not intended to limit the invention to the particular formdisclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the present invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Herein we describe a system and method for the identification ofpatterns. The system and method may discriminate between patterns thatmay be generated. The system may include identification markings and/orsensor arrays. Patterns of elements in an array of an identificationmarking and/or a sensor array may facilitate identification of itemsand/or analytes.

In an embodiment, alignment markers may be positioned proximate an arrayof elements. An array may include, but is not limited to anidentification marking and/or sensor array. An array of elements may beused to create a unique identification code. The unique identificationcode, or identification marking, may be used to identify an object or acondition. Alignment markers may be distinguishable from elements in asensor array and/or identification marking. Alignment markers may bedistinguishable from other alignment markers. Three or more alignmentmarkers may be positioned proximate a pattern. Two alignment markers maybe positioned on a first edge of a pattern. A third alignment marker maybe positioned on an edge adjacent to the first edge of a pattern.Alignment markers may be positioned such that rotation and/ormirroredness of a pattern may be determined.

In some embodiments, first alignment markers are identified. A rotationand mirroredness of a pattern may then be determined fromcharacteristics of alignment markers. Incorporating the rotation andmirroredness information may aid accurate identification of the pattern.

The systems and methods may include identifying an identificationmarking. An identification marking may be used to identify an object ora condition. An identification marking may be placed on an item. Anidentification marking may be used to identify a condition including,but not limited to, a chemical present, and/or electrical state. An itemmay include, but is not limited to any object, such as an item in astore, a piece of paper, and/or a shipping box. In some embodiments, anidentification marking may include an array of elements and three ormore alignment markers. The orientation of the array may be determinedby the position of one or more alignment markers. Alignment markers maybe positioned to facilitate determination of the orientation of thearray. Alignment markers may have a shape, size, and/or color related toinformation about the elements in the array, such as the number ofelements in the array and/or the size of the array. Each alignmentmarker may provide information related to the array of elements. In anembodiment, a relationship between two or more alignment markers mayprovide information about the array. Information about the array mayinclude the number of elements in the array, the size of the array, thedistance between elements in the array, the center of the array, and/oredges of the array.

Elements may be positioned in a predetermined pattern. The predeterminedpattern may include one or more alphanumeric characters. Elements mayhave a predetermined shape and/or size. Elements may be substantiallycircular, substantially oval, substantially square, substantiallyrectangular, or irregularly shaped. In certain embodiments, elements mayinclude a plurality of dots, lines, letters, numbers, and/or othershapes. Elements may be lines of varying widths.

In one embodiment, a shape of an element may be different from a shapeof one or more alignment markers. In an embodiment, shapes of all of theelements may be different from shapes of all the alignment markers. Thesize, shape, and/or color of an element may be different from the sizeof an alignment marker. Elements and alignment markers may be similar.Elements and alignment markers may be distinguishable. Alignment markersmay be approximately two times the size of an element.

In certain embodiments, elements in an identification marking mayinclude one or more error checking elements. In an embodiment, errorchecking elements may be used to determine whether errors occurred whenthe elements are read.

In some embodiments, an item may include an identification marking.During use, a detector may scan an identification marking. In manyinstances, the identification marking may be in a random orientationwith respect to the detector. Thus, an array displayed on theidentification marking may be rotated or otherwise disoriented withrespect to the detector. Generally, in order to determine the pattern, adetector calculates the proper orientation of the array before analyzingthe pattern. A detector may detect the size and/or position of alignmentmarkers and/or elements to facilitate a proper orientation of the array.A detector may recognize the identification marking on an item. Adetector may recognize the identification marking on an item and recallinformation associated with the item, such as price, inventory size,and/or related items.

In some embodiments, detecting an identification marking may includescanning an identification marking, identifying the three or morealignment markers proximate an array of elements in the identificationmarking, determining the position of one or more elements, determiningproperties of the array, and/or determining the predetermined pattern.In an embodiment, identifying three or more alignment markers mayinclude determining a distance from one alignment marker to otheralignment markers. Distances between alignment markers may be comparedto predetermined possible distances.

Determining properties of the array may be based on identified alignmentmarkers. In an embodiment, a property of the array may include thecenter of the array. A center of the array may be determined from afirst and a second alignment marker. Other properties of the array mayinclude mirroredness and/or rotation.

Mirroredness may be determined from a position of one or more alignmentmarkers. Relative positions of alignment markers may determineproperties of an array. In an embodiment determining the mirroredness ofan array may include determining the position of at least threealignment markers, determining an angle between a first and a secondalignment marker, determining an angle between a first and thirdalignment marker, and/or comparing the angle between the first andsecond alignment marker to the angle between the first and thirdalignment marker. Angles may be measured on a Cartesian coordinatesystem. A first alignment marker may be positioned at the origin of aCartesian coordinate system for angle measurements.

Determining the rotation of an array may include first identifyingpositions of at least two alignment markers. An angle between twoalignment markers may be determined, where one of the alignment markersis positioned at the origin of a Cartesian coordinate system.

Elements in an array may form a pattern. A pattern may include, but isnot limited to, a character, a word, a number, a pattern or dots, and/ora pattern of lines. Determining a predetermined pattern may includecomparing a pattern of the element in the array to a database of knownpatterns. Alignment markers and/or elements may facilitate determiningthe predetermined pattern.

In certain embodiments, an identification marking may include aplurality of alphanumeric characters. Alphanumeric characters mayinclude dots and/or lines (such as produced by an ink-jet printer).Alphanumeric characters, alternatively, may be formed by a laserprinter. Three or more alignment markers may be positioned proximate agrouping of alphanumeric characters and/or each of the alphanumericcharacters. In an embodiment, a group of alphanumeric characters lessthan the total number of alphanumeric characters may be associated withthree or more alignment markers. Alignment markers may facilitateidentification of array properties such as rotation, mirroredness, arraysize, array shape, element size, total number of elements in the array,and/or a center of an array.

Recognizing identification markings may be useful in item recognition.For example, a product in a grocery store may have a brand name and aproduct name on the product packaging. The brand name and/or productname may be an identification marking. Alignment markers may bepositioned proximate the brand name and/or product name to facilitateidentification of the product. A database may include pricing and/orinventory information about the product. When a consumer purchases theproduct, the product may be identified by the identification marking anda database may be used to obtain pricing and/or inventory informationabout the product.

The system and method of recognizing identification markings may beperformed by a computer system. In one embodiment, a system and methodfor image recognition may include program instructions executable by aCPU in a computer system. A system may include a carrier medium withprogram instructions for image recognition. A computer or computersystem may typically include components such as CPU with an associatedmemory such as floppy disks and/or CD-ROMs. Memory may store programinstructions for computer programs. Program instructions may beexecutable by CPU. The term “memory” is intended to include anyinstallation medium, e.g., a CD-ROM or floppy disks, a computer systemmemory such as DRAM, SRAM, EDO RAM, Rambus RAM, etc., or anynon-volatile memory such as a magnetic media, e.g., a hard drive oroptical storage. Memory may also include other types of memory orcombinations thereof. In certain embodiments, a system and method forimage recognition may include a carrier medium with programinstructions.

The system and method may include identifying analytes using a sensorarray. The system may identify an analyte. The system may discriminatebetween patterns generated by a sensor array. A pattern may beassociated with an analyte. The sensor array may include sensingelements and alignment markers. The alignment markers may be associatedwith the orientation of the sensor array. The sensing elements mayproduce a signal in the presence of an analyte. An aspect of the systemis that the array may be formed using a microfabrication process, thusallowing the system to be manufactured in an inexpensive manner.

The system may identify the orientation of a sensor array from alignmentmarkers. The system may determine the pattern generated from the sensorelements. The system may determine the analyte associated with thepattern by using information about the orientation of the pattern. Thesystem may determine the identity of an analyte present in the array byrecognizing the pattern of sensing elements in the array.

In some embodiments, a sensor array may detect analytes. A sensor arraymay include an array of sensing elements and three or more alignmentmarkers. Sensing elements may produce a detectable signal in thepresence of an analyte. Alignment markers may be positioned proximatethe array. Alignment markers may be formed on a support member of asensor array. Alignment markers may be positioned to facilitatedetermination of the orientation of the array. Alignment markers mayhave a shape, size, and/or color related to information about theelements in the array, such as the number of elements in the arrayand/or the size of the array. Each alignment marker may provideinformation related to the array of elements. In an embodiment, arelationship between two or more alignment markers may provideinformation about the array. Information about the array may include thenumber of elements in the array, the size of the array, the distancebetween elements in the array, the center of the array, and/or edges ofthe array.

The system may include sensing elements as described in U.S. PatentApplication No. 2003-0003436 A1, “The Use of Mesoscale Self-Assembly andRecognition to Effect Delivery of Sensing Reagent for Arrayed Sensors,”to Mayson et al. published on Jan. 2, 2003, which is incorporated hereinby reference. The sensing elements may be arranged in an array. Thearray, in some embodiments, is made of a plurality of different sensingelements disposed within a supporting member. Each of the differentsensing elements may have a shape and/or a size that differs from theshape and/or size of the other sensing elements. The shape and/or sizeof the sensing element may be associated with a specific analyte orcombination of analytes. Thus, the presence of a particular analyte maybe determined by the observance of a signal from a sensing elementhaving a predetermined shape and/or size. This offers an advantage overconventional systems, where the location of the particle, rather thanthe shape and/or size of the particle, determines the identity of theanalyte.

In some embodiments the array is a microfluidic array. The sensingelement of the microfluidic array may be a cavity. In some embodiments,the sensing element may be one or more particles positioned in a cavityin the microfluidic array. The particle may generate a signal in thepresence of an analyte. Signals generated by particles may form apattern. A pattern may be associated with an analyte. The microfluidicarray may include a plurality of cavities. A particle may be loaded in acavity of the microfluidic array by pipette. More than one particle maybe loaded into each cavity of the microfluidic array. Examples ofparticle based analyte detection systems that may incorporated themethod of image recognition described herein are described in U.S. Pat.No. 6,649,403 entitled “Method of Preparing a Sensor Array” to McDevittet al., which is incorporated herein by reference.

An array may be a plurality of regions of support. In certainembodiments, the array may be a support member in which sensing elementsare positions on the support member where a receptor is positioned orcoupled. An inkjet delivery system may deposit nanoliter and/orpicoliter volumes onto specific positions on the array. In anembodiment, the specific positions on the array may be charged surfacesthat inhibit movement of the deposited volumes.

In some embodiments, the sensing elements in an array may be arranged ina pattern of dots. The sensing elements may produce a signal in thepresence of an analyte. Specific patterns of dots may be associated witha specific analyte.

A sensor array may include sensing elements and alignment markers.Sensing elements may be a variety of shapes, sizes, and/or colors.Sensing element may have a predetermined shape. Sensing elements mayhave a different shape than alignment markers. Sensing elements may besubstantially circular, substantially oval, substantially square,substantially rectangular, or irregularly shaped. Sensing elements maybe shaped as a letter and/or a number. Sensing elements may be lines ofvarying widths.

In an embodiment, sensing elements possess the ability to bind ananalyte of interest and/or to create a signal. A sensor array may beuseful for biosensor identification. A sensing element may include aprobe for detecting a complementary nucleic acid. A sensing element mayinclude one or more receptor molecules which posses the ability to bindan analyte of interest and to create a signal. In an embodiment, areceptor molecule may be capable of binding with more than one analyte.A receptor may be included in a sensing element due to its interactionwith an analyte. In some embodiments, a sensing element may include oneor more receptor molecules and one or more indicators. A receptormolecule may be able to bind to an analyte of interest. Upon bindingwith an analyte of interest, a receptor molecule may cause the indicatormolecule to produce a signal.

A receptor may be loaded onto a sensing element. A receptor may becoupled to a sensing element. A receptor may be configured to produce asignal in the presence of one or more analytes. Receptor molecules mayinclude naturally occurring or synthetic receptors formed by rationaldesign or combinatorial methods. Natural receptors include, but are notlimited to, DNA (single or double stranded), RNA, proteins, enzymes,oligopeptides, antigens, organic molecules and/or antibodies.

In some embodiments, a platform-independent probe loading methodology(“multiplexing”) may be used to load receptors on sensing elements, asdescribed in U.S. patent application Ser. No. 10/832,469 to Schmid etal., entitled “SYSTEM AND METHOD FOR THE DETECTION OF ANALYTES” filed onApr. 26, 2004, which is fully incorporated herein by reference as if setforth herein. Multiplexing may increase the array's density not byadding features to the array, but rather by increasing the array'sdensity by increasing the number of probes that may be distributedwithin the array's original number (quantity) of features.Feature-multiplexing breaks from the status quo of placing each probe onits own exclusive sensing element in order to index the array.Feature-multiplexing indexes an array by placing a probe at a uniquecombination of sensing elements. Using this methodology, a given numberof (n) of sensing elements may be used to deploy a much greater quantity(up to 2n−2) of probes. Because there is this exponential relationshipbetween the number sensing elements and the number of probes an arraymay accommodate, this methodology can dramatically augment the number ofanalytes an array may be used to detect. In some embodiments,multiplexing may be enhanced by use of a parity-sensing element, whichmay help identify the specific analyte that is interacting with one ormore sensing elements when multiple analytes may have a similar code.

In some embodiments, one or more probes may be loaded onto one or moresensing elements. Each individual sensing element may have a uniqueloading of one or more probes. The combination of the individual sensingelements may represent an encoding sequence of one or more analytes. Thecombination of sensing elements may produce a signal that may beinterpreted as a code or pattern. The code or pattern, represented bythe sensing elements, may be used to identify the particular analyte oranalytes that are present. Multiplexing may decrease the number ofexperiments a researcher would need to perform in order to screen forthe presence of a large set (greater than the current capacity ofexisting arrays) of analytes. Fewer experiments equate to preparingfewer samples and using fewer detection devices, and both of theseoutcomes are favorable to the industry.

A detector may facilitate identification of an analyte, alignmentmarkers, and/or sensing elements. During use, a detector may scan anarray. In many instances, the array may be in a random orientation withrespect to the detector. Thus, a detector may rotate or otherwiseoriented the array with respect to the detector. Generally, in order todetermine the pattern a detector calculates the proper orientation ofthe array before analyzing the pattern. A detector may detect the sizeand/or position of alignment markers and/or elements to facilitate aproper orientation of the array. A detector may detect and/or identifythe alignment markers and/or sensing elements. A detector may be coupledto a processor. A detector may use detected alignment markers and/orsensing elements to identify an analyte present in the sensor array.

In some embodiments, detecting an analyte may include, passing a fluidover a sensor array, scanning the sensor array, identifying alignmentmarkers, determining properties of the array, and/or determining thepredetermined pattern. As the fluid passes over the sensor array, one ormore sensing elements may produce a signal. In an embodiment, sensingelements that interact with the analyte in the fluid may produce adetectable signal. Identifying alignment markers may include determiningthe position of alignment markers and sensing elements and thenidentifying the alignment markers. In an embodiment, may includedetermining a distance from one alignment marker to other alignmentmarkers. Distances between alignment markers may be compared topredetermined possible distances.

Determining properties of the array may be based on identified alignmentmarkers. In an embodiment, a property of the array may include thecenter of the array. A center of the array may be determined from afirst and a second alignment marker. Properties of the array may includemirroredness and/or rotation.

Mirroredness may be determined from a position of one or more alignmentmarkers. Relative positions of alignment markers may determineproperties of an array. In an embodiment determining the mirroredness ofan array may include determining the position of at least threealignment markers, determining an angle between a first and a secondalignment marker, determining an angle between a first and thirdalignment marker, and/or comparing the angle between the first andsecond alignment marker to the angle between the first and thirdalignment marker. Angles may be measured on a Cartesian coordinatesystem. A first alignment marker may be positioned at the origin of aCartesian coordinate system for angle measurements.

Determining the rotation of an array may include first identifyingpositions of at least two alignment markers. An angle between twoalignment markers may be determined, where one of the alignment markersis positioned at the origin of a Cartesian coordinate system.

Sensing elements may produce a detectable signal in the presence of ananalyte. A pattern may be generated by the sensing elements that producea signal due to the presence and/or absence of an analyte. Determining apredetermined pattern may include comparing a pattern of the element inthe array to a database of known patterns. Alignment markers and/orelements may facilitate determining the predetermined pattern. A patternmay be generated by sensing elements in a sensor array.

The system and method of image recognition may be performed by acomputer system. In one embodiment, a system and method for imagerecognition may include program instructions executable by a CPU in acomputer system. A system may include a carrier medium with programinstructions for image recognition. A computer or computer system maytypically include components such as CPU with an associated memory suchas floppy disks and/or CD-ROMs. Memory may store program instructionsfor computer programs. Program instructions may be executable by CPU.The term “memory” is intended to include any installation medium, e.g.,a CD-ROM or floppy disks, a computer system memory such as DRAM, SRAM,EDO RAM, Rambus RAM, etc., or any non-volatile memory such as a magneticmedia, e.g., a hard drive or optical storage. Memory may also includeother types of memory or combinations thereof. In certain embodiments, asystem and method for image recognition may include a carrier mediumwith program instructions.

Arrays may include elements and alignment markers. Arrays may include,but are not limited to, identification markings and/or sensor arrays.Elements may include elements in an array of an identification markingand/or sensing elements in a sensor array. Alignment markers may besimilar to elements in an element array of an identification marking.Alignment markers may be similar to sensing elements of a sensor array.An alignment marker may indicate the rotation and/or mirroredness of anarray. Alignment markers may be positioned proximate an array. Alignmentmarkers may facilitate identification of patterns generated by an array.In some embodiments, alignment markers may provide orientationinformation to the analyte identification system to facilitate accurateidentification of an analyte. In an embodiment, alignment markers mayreduce inaccurate identifications due to the orientation of a patternrelative to a detector.

In some embodiments, three or more alignment markers may be positionedproximate an array. In an embodiment, utilizing three or more alignmentmarkers may facilitate recognition of the angle, mirroredness, andposition of an array. The use of three or more alignment markers mayfacilitate accurate recognition of array patterns. An array pattern mayinclude but is not limited to a pattern formed by elements in anidentification marking and/or a pattern generated by sensing elements ina sensor array. The alignment markers each may be substantiallycircular, substantially square, substantially oval, substantiallyrectangular, and/or irregularly shaped. In some embodiments, thealignment markers may have a shape that differs from the shape ofanother alignment marker. Alignment markers may have substantiallysimilar shapes. Substantially circular alignment markers may be easierto identify by a computer. The circular alignment marker may be a dot. Adot may facilitate computer recognition because a dot appears the sameregardless of rotation and/or mirroredness. A dot may be an easy shapeto form using photolithography. In an embodiment, alignment markers mayhave similar sizes. Alignment markers with similar sizes may be moreeasily recognized.

Alignment markers and elements may have similar sizes. Alignment markersand elements may have substantially different sizes. In someembodiments, alignment markers may be larger in size than elements. Inan embodiment, an alignment marker may be approximately two times thesize of an element. Using substantially different sized alignmentmarkers and elements may have advantages compared to similarly sizedalignment markers and elements. When an alignment marker is larger thanan element, distinguishing alignment markers from elements may befacilitated. In some embodiments, the image recognition system mayidentify alignment markers before identifying the elements. In someembodiments, a computer may be utilized to recognize differences insizes. In an embodiment, the center position of a large shape is morereadily determined than in a small shape. Identification of a centerposition of an alignment marker may facilitate accurate array angledeterminations.

In certain embodiments, the size of the alignment marker may conveyinformation about the array. For example, an array designed to identifya group of analytes may include an alignment marker of a predeterminedsize. A fluid may pass over several sensor arrays. Analytes in the fluidmay couple with one or more sensing elements. An analyte may be detectedby recognizing the patterns of the sensor arrays and/or sizes ofalignment markers on the sensor arrays. In an embodiment, a size of analignment marker may indicate a group with which an item is associated.Identification of a group an item is associated with may facilitatelocation of information associated with an item in a database (i.e., aprice of an item, other colors of an item available).

In one embodiment, the size of an alignment marker may indicate the sizeof an element. In an embodiment, an alignment marker may be twice thesize of an element in an array. Knowledge of relative sizes of alignmentmarkers and elements may facilitate identification of alignment markers.Size information may distinguish between alignment markers and elements,facilitating accurate identification of array patterns.

In some embodiments, the system may include identifying alignmentmarkers prior to identifying elements. Information about the relativesizes of the alignment markers and elements may narrow searches forelements to objects in a determined size range. In an embodiment,alignment marker and element size ranges may be input into a computerexecuting the image recognition method. Alignment markers may beconfigured to reveal the size range of elements (i.e., a size and/or ashape of an alignment marker may indicate the size range of elementsassociated with the alignment marker).

The size of an alignment marker may indicate the number of elements inan array. In some embodiments, a larger alignment marker may indicate agreater number of elements in an array. In some embodiments, at leastone alignment marker may indicate the number of elements in the array.In some embodiments, each alignment marker may provide differentinformation about the array. In some embodiments, a combination ofalignment markers may provide information about the array to facilitateidentification of a pattern. Similarly, shape, color, and/or relativepositions may indicate information about the array or information aboutelements in the array.

The position of the alignment markers may convey information about anarray. In some embodiments, a distance between a first alignment markerand a second alignment marker may be approximately twice the distancebetween two adjacent elements in the array. In an embodiment, a distancebetween a first alignment marker and a third alignment marker mayindicate the location of the center of an array. In an embodiment, adistance between an alignment marker and the array may be approximatelyequal to a diameter of an element.

The positioning of alignment markers may identify one or more edges ofthe array. In an embodiment, alignment markers may identify a first edgeand a second edge substantially perpendicular to the first edge. Two ormore alignment markers may be positioned proximate a first edge of anarray and one or more alignment markers may be positioned proximate asecond edge of the array. The size of an alignment marker may indicatethe size of an array.

The system may search an area proximate the alignment markers forelements and/or signals generated by elements. Limiting the area ofsearch may speed up image recognition and/or reduce erroneous readingscaused by misidentified elements. Information obtained from thealignment markers may limit a search area for elements in the array. Inan embodiment, information obtained from the alignment markers maydefine the search area for the elements in the array.

When center point, bottom and left edge locations of an array aredetermined, the size of the array may be determined. Knowledge of thesize of the array may restrict the search area for pattern to accuratelyidentify the size of a pattern. When alignment markers are configured toprovide information about center point, bottom, and left edge locations,an array may have various shapes. In some embodiments, an array may besubstantially square, substantially rectangular, substantiallytriangular, and/or substantially circular.

Proper positioning of alignment markers may be determined using a test.The test may ensure that when a rotated and/or mirrored first array ispositioned over a second array such that alignment marks from the firstand second array overlap, the regions occupied by the elements of thefirst and second array do not overlap. In some embodiments, alignmentmarkers in different arrays do not have substantially similar shapes.The dot array regions may overlap when the alignment markers do not havesubstantially similar shapes.

The use of three or more alignment markers proximate an array may beextended to other recognition applications. For example, the system canbe used to assist pattern recognition software, such as opticalcharacter recognition (OCR) applications. OCR techniques are very goodat identifying letters and numbers with varying sizes and fonts. OCRtechniques have relatively high defect tolerance and imperfectcharacters may often be correctly detected. OCR is designed to recognizecharacters in a line of text, (e.g., characters that are all perfectlyupright). If the characters are rotated even a small amount, recognitionmay fail (see FIG. 5). Thus, current OCR techniques may not be usefulfor applications where letters or patterns are at varying angles (forexample, alphabet soup).

The system may be utilized with OCR techniques. In some embodiments,alignment markers may be placed proximate a character. Three or morealignment markers may be placed around a single character or a group ofcharacters. Alignment markers may be used to determine the rotation andmirroredness of the character. Then, the character may be redrawn in anupright and un-mirrored fashion and fed into an OCR program forrecognition. In this way, the advantages of OCR, such as font size, typeindependence, and defect tolerance, may be utilized.

The system may take a digital image of an array pattern and determinethe pattern regardless of orientation and/or mirroredness. The systemmay be two-fold. The system may first extract location and sizes of thealignment markers in the array system. In some embodiments, the systemmay first use machine vision techniques and algorithms to extract thelocations and sizes of the alignment markers and elements in the image.In some embodiments, alignment markers and elements may be similar insize, shape, and/or color. In some embodiments, the alignment markersmay differ from the elements in size, shape, and/or color. The systemmay use size and location information from alignment markers andaccurately determine a pattern.

Several techniques to extract size and location information of elementssuch as dot shaped elements in an image are generally known in the art.Some techniques are faster and/or more robust than other techniques. Thesystem may include computer techniques to extract size and locationinformation of elements in an array.

In some embodiments, a list of components may be obtained from an imageof the array pattern and/or the array pattern itself. The list ofcomponents may include alignment markers and elements. The alignmentmarkers may be differentiated from the elements in the list ofcomponents.

In certain embodiments, the size of an alignment marker may be differentfrom the size of an element. In some embodiments, the size of onealignment marker may be different from the size of a different alignmentmarker for the same array. Alignment markers associated with an arraymay have similar sizes and/or shapes. Alignment markers associated withseveral arrays may have similar sizes and/or shapes. In someembodiments, the size of an alignment marker may correspond to an array.If the size of alignment markers is specified, then alignment markersmay be identified from the list of components based on size. In someembodiments, the size of an alignment marker may be in a specifiedrange. In some embodiments, the sizes of alignment markers may be in aspecified range among several ranges associated with alignment markersfor arrays.

In some embodiments, a range containing the specified size of analignment marker may be utilized to search the list of components. Insome embodiments, the alignment markers may be approximately 50 pixels.A component list may be searched for alignment markers that have sizesin the range of approximately 45 pixels to approximately 55 pixels.

In some embodiments, a size of an alignment marker may not be previouslyspecified. The size of an alignment marker may differ from the size ofan element. An alignment marker may be larger than an element.Alternatively, an alignment marker may be smaller than an element. Ahistogram of diameters for the items in the list of components may beconstructed to facilitate identification of alignment markers. Thehistogram may have peaks associated with sizes of alignment markersand/or elements. In some embodiments, the histogram may have two peakswhere one peak may be associated with the size of the alignment markersand the second peak may be associated with the size of the elements.Alignment markers may be identified within the list of components basedon the size determined from the histogram. A range may be used toidentify alignment elements in the list of components to decrease theeffects of noise, debris, and/or defects in alignment marker production.

In some embodiments, the size of an alignment marker may be input intothe system to identify alignment markers. In an embodiment, three ormore of the largest items, with respect to size, in the list ofcomponents are averaged. The averaged size may correspond to a size ofalignment markers. In some embodiments, a tolerance is used with theaveraged size to obtain a range. The list of components may be searchedfor alignment markers by identifying items in the list of componentswithin the range of sizes.

In some embodiments, a predetermined number of alignment markers may beidentified with an array. An array may be associated with threealignment markers. Once alignment markers have been identified, groupsof three alignment markers may be found. In some embodiments, more thanthree alignment markers may be associated with an array. The alignmentmarker diameter may be related to the distance between alignmentmarkers. The distance between the alignment markers may be calculatedfrom the alignment marker diameter D_(L):

Distance between alignment markers 1 and 2: d ₁₂=2×D _(L)

Distance between alignment markers 1 and 3: d ₁₃=3.25×D _(L)

Distance between alignment markers 2 and 3: d ₂₃=√{square root over((3.25D _(L))²+(1.25D _(L))²)}{square root over ((3.25D _(L))²+(1.25D_(L))²)}

where d₁₂, d₁₃, and d₂₃ are center-to-center distances between alignmentmarkers.

A method may be used to identify groups of alignment markers associatedwith an array. First, an alignment marker may be selected and theselected dot may be called the “current dot”. Next, distances betweenthe current dot and all other alignment markers may be calculated andstored. If two of the calculated distances are d₁₂ and d₁₃ then thecurrent dot might be alignment marker 1. Then, the distance betweenalignment markers 2 and 3 may be calculated. If the distance is equal tod₂₃, then a group of alignment markers associated with an array may havebeen found.

In some embodiments, after the distances between the current dot and thealignment markers are calculated, two of the calculated distances may bed₁₂ and d₂₃ such that the current dot may be alignment marker 2. Then,the distance between alignment markers 1 and 3 may be calculated. If thedistance is equal to d₁₃, then a group of alignment markers associatedwith an array may have been found.

In certain embodiments, after the distances between the current dot andthe alignment markers are calculated, two of the calculated distancesmay be d₁₃ and d₂₃ such that the current dot may be alignment marker 3.Then, the distance between alignment markers 1 and 2 may be calculated.If the distance is equal to d₁₂, then a group of alignment markersassociated with an array may have been found. In some embodiments, oncean alignment marker is associated with a group of alignment markers itis not considered in determining groups of alignment markers. The use ofa current dot and calculated distances may identify the groups ofassociated alignment markers from a list of components.

Distance calculations may be calculated accounting for tolerance ranges.In some embodiments, a tolerance range may be ±10%. A tolerance rangethat is too large may cause ranges for distances between alignmentmarkers to overlap. Overlapping alignment marker distances may causeinaccurate determinations of orientations of arrays.

Once alignment dots have been grouped, the rotation and the mirrorednessof an array may be determined. An embodiment of the method to determinerotation and mirroredness is described below.

-   -   a. The center of alignment marker 1 is placed at the origin of        an x-y coordinate system and the positions of the other        alignment markers are calculated relative to the origin, as        shown below (see FIG. 9):

X_(1r) = 0 Y_(1r) = 0 X_(2r) = X₂ − X₁ Y_(2r) = −(Y₂ − Y₁) X_(3r) = X₃ −X₁ Y_(3r) = −(Y₃ − Y₁)

-   -   Where X₁, X₂, X₃, Y₁, Y₂, and Y₃ are the actual coordinates of        alignment markers 1, 2 and 3 and X_(1r), X_(2r), X_(3r), Y_(1r),        Y_(2r), and Y_(3r) are the coordinates of the alignment markers        1, 2, and 3 relative to dot 1. The calculations for the Y        coordinates are made negative because in the image coordinate        system, Y increases downward, while in a Cartesian coordinate        system, Y increases upward.    -   b. The angle that alignment markers 1 and 3 make with the x-axis        (θ₁₃) may be calculated, as follows:

$\theta_{13} = {\tan^{- 1}\left( \frac{Y_{3r}}{X_{3r}} \right)}$

-   -   Thus, an angle of 0° is calculated when alignment markers 1 and        3 are in a horizontal plane. This measurement is used to specify        the rotation of the array.    -   c. The angle that alignment markers 1 and 2 make with the x-axis        (θ₁₂) may be calculated, as follows:

$\theta_{12} = {\tan^{- 1}\left( \frac{Y_{2r}}{X_{2r}} \right)}$

-   -   d. To determine if the array is mirrored, θ₁₃ and θ₁₂ are        compared. If θ₁₃ is greater than θ₁₂, then the array is not        mirrored, otherwise the array is mirrored.    -   e. A check may be calculated to make sure the three alignment        dots are in a proper formation and/or properly grouped. The        angle between dots 2 and 3 may be calculated, as follows:

θ₂₃=θ₁₃−θ₂₃

-   -   The angle θ₂₃ should always equal ±45°. If angle θ₂₃ does not        equal ±45°, then there may be problem with the array and the        results may be discarded.    -   f. Steps a-e may be repeated until the rotation and mirroredness        of all groups have been calculated.

Dot patterns and/or other patterns may be identified by the system. Thepositions of the alignment markers with respect to the array may changethe equations below used in an embodiment of the invention. Theequations may be altered to account for the position of the alignmentmarkers. FIG. 6 shows an embodiment of the array. The equations belowmay be associated with the 5 by 5 array similar to the array of FIG. 6.

After the rotation and mirroredness of an array is known, the pattern ofthe elements of an array may be determined. An embodiment for thedetermination of the array pattern where elements of the array arearranged in a rectangular pattern is described below:

-   -   a. The locations of each element in the array may be calculated        using the following equations:

X _(r,c) =X ₁ +D _(1r,c)×cos(θ₁₃±θ_(1r,c))

Y _(r,c) =Y ₁ −D _(1r,c)×sin(θ₁₃±θ_(1r,c))

-   -   where X_(r,c) and Y_(r,c) are the coordinates of the element in        row r, column c; X₁ and Y₂ are the coordinates of alignment        marker 1; D_(1r,c) is the distance from alignment marker 1 to        the element in row r, column c; and θ_(1r,c) is the angle that        element at row r, column c makes with alignment marker 1. The ±        mark inside the above two equations indicate that a minus sign        should be used with the formula if the array is mirrored;        otherwise, use a plus sign is used. The rows and columns are        referenced from top to bottom and from left to right,        respectively. Thus, the upper left element in FIG. 6 is in row        1, column 1, and the bottom right element is in row 5, column 5.    -   The distance D_(1r,c) is calculated with the following equation:

$D_{{1r},c} = \sqrt{\left( \frac{D_{L} + {4{D_{L} \cdot c}}}{4} \right)^{2} + \left( \frac{D_{L}\left( {{2r} - n_{r} - 1} \right)}{2} \right)^{2}}$

-   -   where D_(L) is the alignment dot diameter, and n_(r) is the        number of rows in the array.    -   The angle θ_(1r,c) is calculated with the following equation:

$\theta_{{1r},c} = {{\tan^{- 1}\left( \frac{2{D_{L}\left( {1 + n_{r} - {2r}} \right)}}{D_{L} + {4{D_{L} \cdot c}}} \right)} + \frac{\pi}{4}}$

-   -   b. Each location at (X_(r,c), Y_(r,c)) is searched for an        element. If an element is in the vicinity, then its row and        column coordinates are recorded. A tolerance range may be used        to search a range around each specified location. The tolerance        range may be ±10%.    -   c. Optionally, error checking is done on the pattern (see        below).    -   d. The determined pattern is compared to a database of known        patterns. If the determined pattern matches a known pattern,        then a computer may retrieve information about the known pattern        from the database. The known pattern may be associated with an        analyte, thus facilitating analyte recognition. The known        pattern may be associated with information about an item with an        identification marking.    -   e. Steps a-d are repeated for all arrays in the image.

In some embodiments, the pattern may not be a regular array of elements.In some embodiments, the array may be a pattern as shown in FIG. 8. Thearray may be an array of characters and/or numbers. An embodiment of thesystem is shown below. The embodiment may be performed to prepare theimage for external pattern recognition software, such as OCR. For eachpattern, a rotation and/or mirroring algorithm is performed:

-   -   a. The size of the pattern is calculated:

X _(size)=2√{square root over ((d ₁₃)²−(d ₁₂+1.25D _(L))²)}{square rootover ((d ₁₃)²−(d ₁₂+1.25D _(L))²)}±2D _(L)

Y _(size)=2d ₁₂+0.5D _(L)

-   -   These equations work when alignment markers 1 and 3 are placed        on the central horizontal and vertical axes, and alignment        marker 2 is placed in line with the bottom edge. The left and        bottom edges are assumed to be located D_(L) away from the        centers of the alignment markers.    -   b. A copy of the unrotated, unmirrored pattern is made with        dimensions X_(size)×Y_(size). This may be done by going through        each pixel in the copied (unrotated) image and copying over the        corresponding pixel in the rotated image. For each pixel in the        copied image with coordinates (X_(c), Y_(c)), the pixel from the        rotated image with coordinates (X_(r), Y_(r)) is copied. The        values for X_(r), Y_(r) are:

X _(r) =X ₁ +D _(1x,y)×cos(θ₁₃±θ_(1x,y))

-   -   where X₁ and Y₂ are the coordinates of alignment marker 1;        D_(1x,y) is the distance from alignment marker 1 to the pixel at        coordinate (X_(c), Y_(c)); and θ_(1x,y) is the angle that the        pixel at coordinate (X_(c), Y_(c)) makes with alignment        marker 1. The ± mark inside the above equations indicates use of        a minus sign if the array is mirrored and use of a plus sign        otherwise. The rows and columns of pixels are referenced from        top to bottom and from left to right, respectively. Thus, the        upper left pixel in the image is at (0,0) and the lower right        pixel is at (X_(size), Y_(size)).    -   The distance D_(1x,y) is calculated with the following equation:

D _(1x,y)=√{square root over ((D _(L) +X _(c))²+(d ₁₂+0.25D _(L) −Y_(c))²)}{square root over ((D _(L) +X _(c))²+(d ₁₂+0.25D _(L) −Y_(c))²)}

where D_(L) is the alignment marker diameter, and d₁₂ is the distancebetween alignment markers 1 and 2.

The angle θ_(1x,y) is calculated with the following equation:

$\theta_{{1x},y} = {{\tan^{- 1}\left( \frac{d_{12} + {0.25D_{L}} - {Yc}}{D_{L} + X_{c}} \right)} + \frac{\pi}{4}}$

-   -   c. Steps a-b are repeated for each pattern in the image.

After the rotation and mirroredness of each array is determined, thepattern is compared to a database of known patterns. If the determinedpattern matches a known pattern, then a computer may retrieveinformation about the known pattern from a database.

Error-Checking/Correction for Arrays

If a dot or element in an array is missing or obscured, then the correctpattern may be misidentified. An error-checking scheme may beimplemented in situations where missing or obscured dots or elementsmight occur.

Some digital error checking and correction algorithms involvetransmitting a certain number of error checking bits along with the databits. In an embodiment, parity checking may be included in the imagerecognition system. In parity checking, a single bit is marked as theparity bit. The rest of the bits are used for data. Each data bit isgiven a value of “1” if it is on or “0” if it is off. Then, the valuesof the data bits are added together. If the sum is even, then the paritybit is assigned “1”. If the sum is odd the parity bit is set to “0”.(This is called even parity—in odd parity, the parity bit is set to 1 ifthe sum of the data bit is odd, either parity system may be used forerror checking.) When the data and parity bits are transmitted, theirsum is calculated at the received end and the parity bit is determined.If the calculated parity bit is the same as the sent parity bit, thenthe data is assumed to be error-free.

In some embodiments, parity checking may be included in the patternrecognition system that includes a 5×5 element array. In someembodiments of a 5×5 element array including dot shaped elements, 24 ofthe dots could be data bits and one dot could be the parity bit.Elements may not be dot shaped, in certain embodiments. Using a singlebit to error-check 24 other bits may not be a very robust system. Ifthere is a single error, then the parity bit may switch and an error maybe detected. If there are two errors in the array, the parity bit mayremain the same and no error may be detected. Therefore, parity errorchecking may be limited to checking only 7-8 bits at a time. In someembodiments, as the number of data bits checked increases, theprobability of having two or more errors increases.

By using a parity checking method involving additional error checkingbits, the system may be more robust. In an embodiment of a 5×5 elementarray, the array could be split into two data sets, one 11 bit set andone 12 bit set, each set may have its own parity bit. Two errors in thearray may be recognizable. If greater robustness is required, the arraymay be further subdivided.

In a system including parity checking, errors may be detected but theymay not be corrected. The Hamming Code is an algorithm that sets errorchecking bits in such a way that single errors can be detected andcorrected. It can be extended to detect (but not correct) double errors.The system of pattern recognition may utilize the Hamming Code. Variousother error checking routines may be used. The error checking routinemay correspond to the level of robustness needed for the system.

FIG. 8 a depicts an embodiment of a 5×5 element array where the elementsare represented by dots numbered 1-25 left-to-right, bottom-to-top. Anembodiment of utilizing the Hamming Code with the 5×5 array, depicted inFIG. 8, to detect errors is described below.

-   -   a. Mark every dot position that is a power of two as an error        checking bit, e.g. 2⁰=dot #1, 2¹=dot #2, 2²=dot #4, etc. The        remaining dots are used for data.    -   b. Each checking bit encodes for the parity of a certain number        of bits:        -   i. Dot #1: Check 1 bit, skip 1 bit, check 1 bit, skip 1 bit,            etc. (Dots 3,5,7,9,11, . . . ) (Dot 1 is ignored since it is            the bit being calculated).        -   ii. Dot #2: Check 2 bits, skip 2 bits, check 2 bits, skip 2            bits, etc. (Dots 3,6,7,10,11, . . . )        -   iii. Dot #4: Check 4 bits, skip 4 bits, check 4 bits, skip 4            bits, etc. (Dots 5,6,7,12,13,14,15, . . . )    -   c. For each error-checking bit, set to “1” if the sum of the        bits it checks for is odd; otherwise set to “0”.    -   d. To extend the algorithm to detect double errors, designate        the last bit as an overall parity bit covering both data and        error checking bits. The values of all previous bits are summed,        and the bit is set to “1” if the sum if odd, otherwise it is set        to “0”. This bit is not included in the above calculations.

FIG. 8 b shows a 5×5 element array with the array labeled as above. Thedata bits are D1-D19, the error checking bits are E1-E5 and the paritybit is P1.

To check a given array for errors, the following is performed:

-   -   a. Calculate the value of each error checking bit and compare it        to the given value. Calculate the value of the parity bit and        compare to its given value.    -   b. A single error may be signaled by errors in one or more error        checking bits and an error in the parity bit, OR no errors in        the error checking bits and an error in the parity bit. It can        be corrected—see step d.    -   c. A double error may be signaled by errors in one or more error        checking bits, and no error in the parity bit. It cannot be        corrected.    -   d. For single errors, add up the bit numbers of each incorrect        error-checking bit. This sum gives the location of the error.        For example, say that error-checking bits at positions 2 and 8        are incorrect. The sum of these position numbers is 10;        therefore, there is an error in bit 10 than can be corrected. If        all the error-checking bits are correct, then the error is in        the parity bit itself.

Example 1 Dot Recognition Algorithm

A fairly quick and simple technique for determining dot sizes andlocations is described below. The system and method may work well forimages with well-formed dots and low noise. The system and method has alow tolerance for defects, such as partial or malformed dots andmiscellaneous debris in the image. The miscellaneous debris may appearsimilar to the dots. Methods that are more robust may be employed withinthe system as previously described, provided that the dot size andlocation information can be fed into the pattern recognition algorithm.

The computerized recognition of patterns may be broken down into severalsteps. Each of these steps is discussed in detail. First, however, abrief discussion about the nature of the images is needed.

The algorithms below describe how to process digital images stored inRGB (red-green-blue) format. This format is standard for computers,cameras, and video displays. Images are comprised of pixels, where eachpixel corresponds to a certain color. A color is made by mixing theprimary colors of light in different intensities (i.e. mixing red, blueand green). Each pixel is assigned an integer number that corresponds toits color. This number typically ranges from 0 to 16,777,215. Thissingle number may be then broken down into three separate integernumbers describing the intensities of the red, green, and blue light.Typically, each of these three numbers may have a range of values from 0to 255, with 0 being no intensity (black) and 255 being the highestintensity. For example, a pixel with RGB values of 255, 128, and 0 maybe the mixture of bright red, medium green, and no blue. This mixture ofcolors may appear orange to the human eye.

Other systems besides RGB exist to describe images. For example, theCMYK (cyan-magenta-yellow-black) format is often used in the printingindustry. It describes the four colors of the inks that are used. TheHSV (hue-saturation-value) format is another common format. There aremany other color formats. Regardless of the format that the image is in,the system and method may work with the appropriate modifications.

Some of the algorithms described below must convert the RGB colorintensity values into a single intensity value (for example, whenconverting the image to grayscale). This conversion is done via the CIE(Commission Internationale d'Eclairage) LAB color model. The human eyemay be responsive to green light, less responsive to red, and leastresponsive to blue. The CIELAB color model may account for human eyeresponsiveness when computing a single intensity from red, green, andblue by weighting each color differently. Green is given the most weight(0.589), followed by red (0.300) and blue (0.111). To construct a singleintensity value, each color value is multiplied by its weight. Then,these values are added together. For example, take the color with RGBvalues 150, 100, and 250, which appears as a pale blue. First, eachcolor is weighted: 150*0.300=45.0, 100*0.589=58.9, 250*0.111=27.8. Thenthese numbers are added to construct the single intensity value:45.0+58.9+27.8=131.7=132. This may appear as a medium gray.

Before any software image processing is performed, an image containingthe pattern(s) is input to the computer. This may be done in any numberof ways. For example, a video camera that is focused on the pattern andcoupled to the computer through a digitizer card can be used. A scannermay be used to scan in a photo of a dot pattern. The image of a dotpattern may be produced in drawing software. Various other methods forinputting images into computers may be used. The image may contain oneor more patterns and may be any size that may fit into computer memoryor disk storage. The image may be in color, grayscale, orblack-and-white. The image file may be in any format (bitmap, JPEG,TIFF, GIF, etc.)

In some embodiments, the entire image is used for recognition of thepattern. Patterns that are cropped short by the sides of the image orare covered by opaque objects may cause inaccurate recognition. Dotpatterns that are separated or in pieces may make pattern identificationdifficult. In an embodiment, there is sufficient contrast between thedot pattern(s) and the background such that the software may “see” them.Sufficient contrast may be as low as a single intensity unit on an RGBscale.

The size of a dot pattern may influence whether a pattern may beaccurately recognized. This may depend on the robustness of the dotrecognition algorithms. A dot pattern may include enough pixels thatindividual dots are distinguishable by computer-aided methods. An imagemay be in sufficient focus for identification. While some defects may betolerated, the defects should be at a level that may not lead toinaccurate recognition. Missing alignment dots may cause inaccuratepattern recognitions.

Once the image is acquired, the actual dots in the dot patterns arerecognized and cataloged. The purpose of this process is twofold: First,the dots specific to the dot patterns are recognized and sorted out fromother artifacts in the image. Second, the sizes and positions of therecognized dots is determined.

FIG. 9 shows a sample image. The method used to recognize the dots inthe image is broken down into several steps. The result of each step isshown in subsequent figures.

This step is not required but it generally improves recognitioncapabilities. Typically the dots in the pattern are a different colorfrom the background. A color filter is applied which eliminates colorsthat are not sufficiently similar to the colors of the dots (see FIG.10). The color filtering method may be as follows:

-   -   a. Pick a color for the filter that corresponds to general tone        of the dots. For example the dots may be a reddish tone. Call        the RGB values of this color R_(f), G_(f), and B_(f).    -   b. Pick a tolerance value T_(f) between 0 and 255. A small        tolerance value means that only colors very close to the filter        color may be accepted. A tolerance between 20 and 40 may give        accurate results.    -   c. Scan through the image, one pixel at a time. Call the RGB        values of the current pixel R_(c), G_(c), and B_(c).    -   d. For each pixel, compute the “distance” between the current        color and the filter color.

D=√{square root over (A _(R)(R _(f) −R _(c))² +A _(G)(G _(f) −G _(c))²+A _(B)(B _(f) −B _(c))²)}{square root over (A _(R)(R _(f) −R _(c))² +A_(G)(G _(f) −G _(c))² +A _(B)(B _(f) −B _(c))²)}{square root over (A_(R)(R _(f) −R _(c))² +A _(G)(G _(f) −G _(c))² +A _(B)(B _(f) −B_(c))²)}

-   -   where A_(R), A_(G), and A_(B) are the red, green, and blue        weighting coefficients for the CIELAB color model (A_(R)=0.300,        A_(G)=0.589, A_(B)=0.111).    -   e. For each pixel, compare the distance D to the tolerance        T_(f). If the distance is less than or equal to the tolerance,        then accept the color and leave it unchanged. Otherwise, color        the pixel black (RGB=0,0,0).

This step is also optional but it can improve recognition capabilities.As shown in FIG. 10, some of the dots have jagged edges and there aresome miscellaneous specks and extraneous debris. These artifacts areconsidered to be noise that may interfere with the recognitionalgorithms. There are several different types of filters than can beused to reduce noise (Gaussian, median, mode, etc.). FIG. 11 depicts theimage after applying a “median” filter.

Small, bright specks existing in an otherwise dark area have aprobability of being noise. Large bright areas are less likely to benoise and more likely to be the “signal”. A noise filter candifferentiate between noise and signal using these criteria. Noise maybe removed or set to black and the signal may kept. As shown in FIG. 11,rough edges, bright spots, and extraneous features may be largelyremoved after filtering.

Image thresholding may be used before using an edge detection routine.Thresholding converts a color or grayscale image into a black-and-whiteimage. Rather than being different colors or shades of gray, the pixelsmay be either on (white) or off (black).

Many algorithms may be employed to perform image thresholding. Anembodiment of image thresholding is described below.

-   -   a. Pick a threshold value T between 0 and 255. The best number        to use depends heavily upon the image characteristics. Pixels        with intensities below this threshold may be turned to black and        pixels equal to or greater than this value may be turned to        white.    -   b. Scan through the image one pixel at a time. For each pixel,        compute a single intensity value I from its three color        intensities:

I=A _(R) ·R _(c) +A _(G) ·G _(c) +A _(B) ·B _(c)

-   -   where A_(R), A_(G), and A_(B) are the red, green, and blue        weighting coefficients for the CIELAB color model (A_(R)=0.300,        A_(G)=0.589, A_(B)=0.111) and R_(c), G_(c), and B_(c) are red,        green, and blue components of the current pixel.    -   c. Compare I to the threshold T. If I is less than T, then        change the current pixel color to black (RGB=0,0,0). Otherwise,        change the current pixel color to white (RGB=255,255,255).

After image thresholding it may be desirable to locate the edge of theelements in a pattern or the edge of the pattern. The edge detectionprocedure may require a binary image or one that has been thresholded.Some edge detection algorithms may not depend on a binary image.

In a binary image, edges are easy to locate. They are simply at pointswhere a white pixel is adjacent to a black one. The edge detectionalgorithm colors the edges white and everything else black. A 1-pixelwide white outline is drawn around all objects (see FIG. 12). Edgedetection may be employed as follows:

-   -   a. Scan through the entire image, one pixel at a time. Get the        color of the current pixel (I_(c)), the pixel to its left        (I_(t)), and the pixel below it (I_(b)).    -   b. Compare the current pixel I_(c) to the one on its left I_(t).        There are three possible cases:        -   i. I_(c)=I_(t): There is no edge. Color the current pixel            black.        -   ii. I_(c)=white, I_(t)=black: There is an edge at the            current pixel. Color the current pixel white, and the pixel            to its left black.        -   iii. I_(c)=black, I_(t)=white: There is an edge left of the            current pixel. Color the current pixel black and the pixel            to its left white.    -   c. Compare the current pixel I_(c) to the one below it I_(b).        There are three possible cases:        -   i. I_(c)=I_(b): There is no edge. Color the current pixel            black.        -   ii. I_(c)=white, I_(b)=black: There is an edge at the            current pixel. Color the current pixel white, and the pixel            below it black.        -   iii. I_(c)=black, I_(t)=white: There is an edge below the            current pixel. Color the current pixel black and the pixel            below it white.

The purpose of the shape detection routine is to find individual objectsin the image and determine their size and location (See FIG. 13). Shapedetection may be an important step because dot array patterns are basedon dot sizes and locations.

The shape detection method described below is a tracing step that tracesaround 1-pixel wide edges. Shape detection may be facilitated bythresholding and subsequent edge detection. Some shape detection methodsmay not require 1-pixel wide edges. Some of these methods trace, whileothers do transforms and histogram analysis. Described below is anexample of a shape detection method.

-   -   a. Scan through the image, one pixel at a time. Get the color of        the current pixel (I_(c)),    -   b. If the current pixel I_(c) is black, then go back to step a.        Otherwise continue to step c.    -   c. If the current pixel is white, then an edge is found. Store        the coordinates of this pixel as X_(c), Y_(c).    -   d. Trace around the edge by looking around the current pixel and        finding adjacent white pixels. Store each pixel found.    -   e. End the tracing when there are no more adjacent white pixels        or when the starting position I_(c), Y_(c) is reached.    -   f. Each trace is considered to be an object. Store the width,        height, area, perimeter, and center point of each object.    -   g. Go back to the starting point X_(c), Y_(c) and continue        scanning with Step a.

Elimination of extraneous objects and debris may reduce the amount ofrecognized objects. To sort dots, elements, or the image to berecognized from debris, several approaches may be taken:

-   -   a. Objects that are not circular can be removed. A roundness        calculation can be performed on the image based on its perimeter        P and its area A:

$R = \frac{P^{2}}{4\pi \; A}$

-   -   For a perfect circle, the roundness R may equal 1. Any other        shape may have a roundness greater than 1. Thus, a threshold        roundness value can be set to remove all shapes with roundness        greater than that threshold.    -   b. Circles have equal heights and widths. Objects with unequal        heights and widths (i.e. objects that are rectangular) can be        removed. A tolerance can be set to define the range of        acceptable height/width ratios.    -   c. If the size of the dots is known, then dots too small or too        large can be excluded. The size of the dots in this case is        area.

Once the pattern has been isolated from the detected image, rotation andmirroredness of the pattern may be determined from alignment markers.Three or more alignment markers may provide information about thepattern orientation to facilitate accurate identification. The isolatedpattern may be compared to a catalog of known patterns where the patternorientation is taken into account.

Various embodiments may also include receiving or storing instructionsand/or data implemented in accordance with the foregoing descriptionupon a carrier medium. Suitable carrier media may include storage mediaor memory media such as magnetic or optical media, e.g., disk or CD-ROM,as well as signals such as electrical, electromagnetic, or digitalsignals, may be conveyed via a communication medium such as a networkand/or a wireless link.

In this patent, certain U.S. patents, U.S. patent applications, andother materials (e.g., articles) have been incorporated by reference.The text of such U.S. patents, U.S. patent applications, and othermaterials is, however, only incorporated by reference to the extent thatno conflict exists between such text and the other statements anddrawings set forth herein. In the event of such conflict, then any suchconflicting text in such incorporated by reference U.S. patents, U.S.patent applications, and other materials is specifically notincorporated by reference in this patent.

Further modifications and alternative embodiments of various aspects ofthe invention will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the invention. It is to beunderstood that the forms of the invention shown and described hereinare to be taken as the presently preferred embodiments. Elements andmaterials may be substituted for those illustrated and described herein,parts and processes may be reversed, and certain features of theinvention may be utilized independently, all as would be apparent to oneskilled in the art after having the benefit of this description of theinvention. Changes may be made in the elements described herein withoutdeparting from the spirit and scope of the invention as described in thefollowing claims.

1-171. (canceled)
 172. A first array positioned over a second array,each array having an orientation that is independent, said orientationcomprising rotation and mirroredness, each array comprising a) sensingelements on a support, said support comprising a front side and backside, wherein one or more sensing elements are configured to produce adetectable signal in the presence of an analyte, said signal detectablefrom either said front side or said back side; and b) alignment markerspositioned proximate to the array, wherein alignment markers arepositioned such that the orientation of each array is determined by theposition of the alignment markers.
 173. The first and second arrays ofclaim 172, wherein said arrays are transparent.
 174. The first andsecond arrays of claim 172, wherein said first array is in a rotatedorientation relative to said second array.
 175. The first and secondarrays of claim 172, wherein said first array is in a mirroredorientation relative to said second array.
 176. The first and secondarrays of claim 172, wherein each array is a 5×5 element array andwherein all of said elements of said first array are mirrored.